In the past three seasons, the Seahawks have started nine players at left guard, eight at left tackle and seven at right guard.

During the same period, they used 10 different starting combinations in 2010, seven in 2009 and eight in 2008. The number of players who comprised these revolving-door units was nine in 2010 and 10 each in 2009 and 2008.

How do they not select an offensive lineman with the 25th pick in the first round of April’s NFL draft? And, add at least one more in the subsequent six rounds, where the Seahawks currently have six picks?

Despite the uncertainty over free agency because the CBA between the owners and NFL Players Association is scheduled to expire March 4, the draft will be held April 28-30 – as will the NFL scouting combine that starts next week in Indianapolis.

EYEING THE DRAFT

The Seahawks currently have seven picks in the April NFL draft as they prepare for next week’s scouting combine in Indianapolis:

First round: 25th pick overall

Second round: 57th pick overall

Third round: No pick, traded the 89th selection overall last year to the Chargers for QB Charlie Whitehurst.

Fourth round: Second pick in the round, which was acquired in the trade that sent WR Deion Branch to the Patriots; traded their own pick, 25th in the round, to the Bills for RB Marshawn Lynch.

Fifth round: 25th pick in the round; also 26th pick, which was acquired in the trade that sent CB Josh Wilson to the Ravens.

Sixth round: Eighth pick in the round, which was acquired in the trade that sent DE Lawrence Jackson to the Lions; traded their own pick, 25th in the round, to the 49ers for DL Kentwan Balmer.

Seventh round: Sixth pick in the round, which was acquired in the trade that sent QB Seneca Wallace to the Browns; traded their own pick, 25th in the round, to the Eagles for OL Stacy Andrews.

Note: Overall selections in rounds 4-7 will be determined after compensatory picks are awarded.

General manager John Schneider and his personnel staff already have been huddling for weeks to prepare for both events.

“It’s really important for us that we have to make sure that we elevate the play of our guys up front on both sides of the ball and their depth,” coach Pete Carroll said during his postseason news conference, addressing the need for offensive linemen while also offering another avenue the team could take with that first-round pick on April 28.

“As we got banged up this year and faced the challenges of having to adjust the roster, we needed to maintain the level of play better than we did.”

Rookie left tackle Russell Okung, second-year right guard Max Unger and veteran left guard Ben Hamilton combined to miss 30 starts because of injuries. With starters out, backups obtained from other teams stepped in – and were in turn replaced by players who had been signed off the street.

Only center Chris Spencer started all 16 regular-season games, and he played much of the second half with a broken hand. Right tackle Sean Locklear was next with 15 starts. But both are scheduled to become unrestricted free agents – whenever free agency might begin.

After those two, it was Stacy Andrews with 12 starts and Okung with 10. But Okung played at less than 100 percent because of the high sprains to both ankles that forced him to sit out 6½ games, while Andrews was inactive for the final three games because he had been ineffective while starting.

No wonder the Seahawks had problems consistently generating the kind of running game that Carroll envisioned in his first season as coach, and the kind of running game he needed to take pressure of quarterback Matt Hasselbeck.

Marshawn Lynch and Justin Forsett combined for a 1,000-yard season, but Lynch’s 573 yards were the lowest total to lead the team since 1984 (327 by David Hughes) and fifth lowest in the 35-year history of the franchise. Too often, Lynch’s best runs came on plays where he managed to get a yard or two despite being hit in the backfield a time or two.

“So that’s really a main focus for us,” Carroll said of getting better and deeper on the O-line, with recently hired Tom Cable now in charge of the unit.

Because they are selecting 25th, the top candidates – Boston College tackle Anthony Castanzo and USC tackle Tyron Smith – are expected to be gone by the time the Seahawks make their first pick. But it definitely helps that the O-line group is what senior personnel executive Scot McCloughan calls the best he has seen in his 16 years in the NFL; so good that as many as eight could go in the first round.

With that said, here’s a look at five linemen who, if available at No. 25, might be able to help the Seahawks:

Gabe Carimi, OT, Wisconsin – The Outland Trophy winner as the nation’s top collegiate lineman, the 6-foot-7, 315-pound Carimi is a powerful run blocker. After Joe Thomas became the third pick overall in the 2007 draft by the Cleveland Browns, Carimi stepped in and started the next four years at left tackle for the Badgers.

“But his large frame and physical game belong on the strong side in the NFL,” said Rob Rang, senior analyst for NFLDraftScout.com.

That would work, with Okung already the starter on the left side for the Seahawks.

Mike Pouncey, OG, Florida – He is the twin brother of Maurkice Pouncey, who started all 16 games for the Pittsburgh Steelers as a rookie and was voted to the Pro Bowl after being the 18th pick in the first round by the AFC Champions last year. Although not considered as good as his brother was coming out, Mike could be a good fit as the Seahawks continue to construct their line – especially the interior – because he has the size (6-4, 310), athleticism and versatility to contribute immediately.

“The problem with Mike Pouncey is that he’s compared to his brother,” ESPN draft analyst Todd McShay said Wednesday during a conference-call interview. “His brother, Maurkice, is just at a different level. Mike is a good player, he really is.

“He moves well. I like his feet and I like his potential to play guard and/or center in the NFL. … His versatility and his quickness really give him a good chance to become one of the upper echelon starters of interior linemen in the NFL three or four years down the road.”

Derek Sherrod, OT, Mississippi – An All-SEC selection the past two seasons, Sherrod also was voted conference offensive lineman of week four times as a senior. He played the left side for the Bulldogs, but has the size (6-6, 312) and skills to move to the right side.

“Sherrod was arguably the most consistent of the tackles at the Senior Bowl and confirmed his first-round grade,” Rang said.

Nate Solder, OT, Colorado – A consensus All-American last season, he has the size (6-8, 315) and athleticism to play the left side. Solder (which appropriately rhymes with Boulder) was a high school tight end, defensive end and linebacker who grew into his role as a dominating tackle for the Buffaloes.

“Arguably the most athletically gifted of this year’s offensive tackles,” Rang said. “If he’s still on the board at No. 25, he would present too much of a valve to pass on.”

Danny Watkins, OG, Baylor – A former hockey and rugby player, as well as part-time firefighter, the native of Kelowna, British Columbia, is 26 and played only two seasons for the Bears. He stepped in at left tackle for Jason Smith, the No. 2 pick overall by the St. Louis Rams in 2009. But Watkins (6-4, 312) showed at the Senior Bowl that he can play guard in the NFL.

“His physical, grappling style is more conducive to guard and he took to the position immediately at the Senior Bowl,” Rang said. “He turned in one of the week’s strongest performances.”

That 25th pick just might fit need for the Seahawks because, as McShay put it, “The best value late in the first round is along the offensive line.”